Lost in Space - A Part of Cassini is Still Out There

November 22, 2017; Srama, Ralf

On September 15, 2017, the incredible journey of the Cassini mission to Saturn came
to an end. The spacecraft vanished into the planet at a speed of 120.000 km/h, like a shooting star
streaking across Saturn’s sky. In the end, Cassini became part of the planet itself.

Now the science team of the Cosmic Dust Analyzer (CDA) led by Ralf Srama of the
University of Stuttgart, has pointed out that one part of Cassini was able to survive the fantastic
twenty-year-long journey. Almost forgotten by humankind over time, one metallic piece survived and
is now travelling through space. In 1997, during the spacecraft's early cruise phase, when Cassini
was still in the vicinity of the Earth, the aluminum cover of the CDA was jettisoned in order to
open the instrument's aperture. This early cover release was necessary in order to start with
measurements of the interplanetary and interstellar dust background.

Image: Cover in space

Slowly tumbling through space, the cover with a mass of two mobile phones travels on
an Earth-like orbit and with an approximate speed of 30 km/s. Models show that the trajectory
sometimes brings the cover close to both Venus and Earth. In 2007, the cover came as close as 4
million kilometers to Earth, which corresponds to roughly 10 times the distance between Earth and
the Moon. Although not confirmed, due to its highly reflective surface, the cover might, in
principle, be observable from Earth by larger telescopes. Researchers investigated whether the
cover might collide with Earth and burn up in our atmosphere as a meteor and were able to rule out
this possibility for at least the next 50 years.

The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian
Space Agency. JPL manages the mission for NASA's Science Mission Directorate in Washington. The
Cosmic Dust Analyzer (CDA) was developed by the Max Planck Institute for Nuclear Physics
(Heidelberg) and the German Space Agency (DLR, Berlin). It is operated by the Institute for Space
Systems (IRS) at the University of Stuttgart (Principal Investigator R. Srama). The project is
supported by the German Space Administration DLR.